The phonon vibration characteristics of the Bi2Sr2-xBaxCuOy (x=0, 0.2，0.4) single crystal samples was studied by using Raman scattering measurement. The exp-erimental results show that in the Raman spectra of the Bi2Sr2-xBaxCuOy system the typical phonon vibrational modes mainly appear in the frequency range of 196, 282-310, 460, 625 and 660cm-1, and the intensities of the 196, 282-310, 625, and 660 cm-1 lines enhance with increasing Ba content x. In previous work, we have studied the influence of Ba-doping on the incommensurate modulation structure of the 2201 phase. On the basis of those results, in this article we analyze the relation of the incommensurate modulation structure and phonon vibration characteristics emphatically, thus point out that the intensifying of the superstructure modulation (i.e. the decr-ease of modulation period) changes the symmetry of the unit cell seriously so that the phonon Raman activity of the unit cell varies obviously.